Fix Pong response attempt-to-encode-oversize-msg panic

Author: TheBlueMatt

src/ln/peer_handler.rs

@@ -409,8 +409,10 @@ impl<Descriptor: SocketDescriptor> PeerManager<Descriptor> {
 
 											18 => {
 												let msg = try_potential_decodeerror!(msgs::Ping::decode(&msg_data[2..]));
-												let resp = msgs::Pong { byteslen: msg.ponglen };
-												encode_and_send_msg!(resp, 19);
+												if msg.ponglen < 65532 {
+													let resp = msgs::Pong { byteslen: msg.ponglen };
+													encode_and_send_msg!(resp, 19);
+												}
 											},
 											19 => {
 												try_potential_decodeerror!(msgs::Pong::decode(&msg_data[2..]));